Selective converting of copper matte



Fb. 22, 1938. L. LARSON El AL 2,109,272

' SELECTIVE ()ONVERTING OF COPPER MATTE v Filed May 21, 1935 4 Sheets-Sheet 1 v 751/; 72 g 1% g 75 17 I SLAG' 7'0 REVERBERATOR/ES V AFTER DURING AFTER AFTER INITIAL FIRST FIRSZ TS/IIMM/NG' CHARGING 'ELOM/ING BLOWING sum POINT/IV FRocFJsJ @I 1 2' 6.

Y 75 /J R 15 75 1 5446' T0 fiEl/E/PBERATO/P/EJ AFTER LAST AFTER AFTER M57 BLOW/N6 mam/vs M/MMl/VG' CHARGING ml? .5146 54/16 INVENTORS LEq/v/mw L /aso/v cfiJH/V C TM/NEAR.

ATTORNEYS CONVERTER 5 Feb. 22, 1938. L LARSON ET AL 2,109,272

I SELECTIVE CONVERTING OF COPPER MATTE I Filed May 21, 1935 4 Sheets-Sheet 4 CONVERTER END OF F' IR8T erg-L5H E 3 A J I 20 77 ,1?

79 101.: sErrL/Nc' CONVERIED m HIGH-60w 541.1751? COPPER B DYE ORDINARY P/FOCEQ'J'.

LOWLD COPPER Q 7 %ZLQMATTORNEYS Patented Feb. 22, 1938 I UNITED STATES PATENT OFFICE sELEo'rrva ooix rn'rmo or oorrnn TTE York

Application May 21, 1535, Serial No. 22,572

5'Clalms.

- The invention aims to provide certain improvements over the known processes of converting copper matte selectively, so as to produce two products, one comparatively high in gold, silver and other impurities, and the other comparatively pure copper. An example of a matte produced by the smelting of raw concentrate in a reverberatory furnace has the following composition approximately:

Copper per cent" 34 Iron do 35 Sulphur do 25 Gold ounces per'ton 0.3 Silver do 2.0

Other impurities may be present in unimportant quantities, and the matte may be of any percent copper suitable for converting operation.

In ordinary non-selective convertingthe molten matte is introduced with a quantity of flux into a vessel similar to a Bessemer converter and air is blown through it. The oxygen in the air blast combines first with the iron and its sulphur. The sulphur burns to sulphur dioxide gas which escapes through the open mouth of the converter, while the iron is oxidized and with the silica in the flux forms a slag. Assuming the oxygen in the blast and the silica in the flux to be provided in proper proportions, at first stage of the process will be complete when the materials in the converter consist of only (1) undecomposed copper sulphide or white metal and (2) slag. The slag is skimmed off and .the blast restored, without fiux because the iron has all been eliminated. The sulphur is oxidized by the blast, burning as before with considerable evolution of heat and formation of 'sulphur dioxide gas which passes off. The copper is more resistant to oxidation and separates in metallic form. When all the sulphur has been oxidized out, the molten copper remaining is transferred in a ladle to a furnace which holds it molten, from which it is cast into pigs of blister copper.

In some cases the first batch of white metal would yield an inconveniently small lot of copper. To get around that difiiculty, more matte is added to the white metal and the process repeated until a sufficiently large batch of white metal is ob tained, whereupon the slag is skimmed and the blowing of the white metal alone is inaugurated.

This one final product contains all of the original impurities, principally precious metals which were incapable of being removed either in the slag or with the gases. The final separation from the copper is accomplished by an electroe lytic process after the blister copper pigs have been transferred to the refinery.

In the present selective method the white metal is produced in the above described manner, or v in any other usual or suitable way, and is blown in'such a way as to obtain two products; one a comparatively high gold bearing copper, which brings a price increasing with its gold content, and the other a blister copper comparatively low in gold content.

The white metal is blown only partially. The blast is turned off for a substantial time to allow all the copperjormed to settle out of the molten mass. This metal contains practically all of the gold in thecharge and a large part of the'silver and other impurities. It is removed, after which the remaining white metal is blown and converted into copper which is low in gold orpractically free from gold.

The process may be varied in detail, three examples being described below.

Example No. 1 is the simplest. The steps, after providing the required quantity of white metal molten in the converter, are as -iol1ows:-

l. Blow the white metal about minutes (as compared with 210 minutes required in the nonselective process). During this short blow about 25 per cent or even less of the total copper originally in the White metal is converted into .metallic copper.

would involve increasing or diminishing the time intervals stated if the process is carried with a larger quantity of white metal or a smaller quantity respectively, the extent of the departure from this example being within the skill of workers in this art. The white metal is poured ofi as completely as possible into ladles or pots for temporary storage; and the settled copper or bottom, which contains a. large part of the gold and a smaller fraction of the silver, is transferred to storage pots and allowed to solidify into buttons which are remelted later on in ordinary blister copper converting or are otherwise utilized.

2. The molten white metal (minus the high gold copper), which was held in temporary storage is poured back into the converter and finished to blister copper as in ordinary converting.

The fraction of the copper so produced is impoverished in gold. Portions of the White metaltemporary storage,

duces a certain quantity of blister copper in particles disseminated throughout the white metal. These particles present a prodigius'area,

of gold-collecting surfaces which are present at the end of the partial blow and which are maintained well into the succeeding settling period.

These dispersed particles constitute the principal reliance of the process for the concentration of the gold, though, of course, there is. some collection of gold through bulk contact with the bottom as the latter settles out.

In the above process the partial blowing and long settling serve to collect a large percentage of the gold by a simple method and equipment, utilizing a single converter.

Example No. 2 is carried out with a pair of converters. The blister copper produced is practically free from precious metals, all of which are collectedin the bottoms. The steps, after producing the required quantities of white metal in two converters designated A and B, are as follows:---

1. Transfer the white metal from converter 13 to converter A. Or the process may be said to begin with an equivalent quantity of white metal provided in any wayin converter A. The white metal is blown for about 90 minutes and the high gold copper allowed to settle out substantially completely in the bottom. The white metal on top is transferred to converter 13. The high gold copper remaining in A is poured into pots, solidified into buttons and remelted later in ordinary blister copper converting.

2. The white metal in converter 13 is blown to low gold blister copper as in ordinary converting.

The chief advantage in this over Example No. 1 is in the maintenance of the low gold white, metal molten by transferring it directly from A to B and thus maintaining a practically continuous blow to the end.

Example No. 3 also utilizes two converters A and B. But the procedure is modified so that there is produced a comparatively small quantity with a higher percentage of gold. The process is the same as that of Example No. 2 through the short blowing of the double charge of white metal in converter A, the allowing of the high gold copper to settle out thoroughly and the transferring of the white metal to converter 13. L 1. Instead of pouring the high gold copper and solidifying it into buttons, it is allowed to remain molten in converter A. i

2. The next stepis to blow the white metal in B to low gold blister copper, which is disposed of as usual. During this blow in B a second cycle of operations is commenced and carried out as follows.

3. Charge converter A with a new supply of.

matte and flux on top of the high gold metal therein, blow'to white metal and slag and skim 015! the slag.

4. Charge A again with matte and flux on top of the white metal left from the previous step aasand at the same time recharge the emptied converter B with matte and flux. Blow both converters to white metal and slag and remove the slag.

5. Transfer the white metal from B to A, blowcycles or more have been completed. When new matte and flux are added to the converter the residual metallic copper in converter A reacts with the new matte and is changed to copper sulphide which immediately dissolves in the matte. Until the last cycle is reached, the onlyv withdrawn product is low gold copper. The residual metallic copper in converter A is passed on from cycle to cycle, carrying with it the gold which it has extracted in the preceding cycles. When it has become sumciently enriched'in gold, the cyclic operation is'brought to an end and the next step follows.

6. A final batch of low gold copper is made from the white metal in B. The enriched bottom remaining in A is supplemented by a charge of new matte and flux and the mixedmass converted into high gold blister copper bythe ordinary procedure. I

'7. The result is a comparatively small quantity of copper in which is collected most of the gold which was carried in a plurality of successive converter charges of matte, from two to sixteen or more double charges in the case described.

For a fuller disclosure of the invention, reference is made to the diagrams illustrated on the accompanying drawings, showing the successive phases of the treatment.

Fig. 1 illustrates stages in the production of white metal fromthe slag. This is the ordinary process, which is followed by blowing all the white metal to ordinary gold-bearing blister copper;

Fig. 2 illustrates Example No. 1 above; Fig. 3.-

ilustrates Example No. 2 above; Fig. 4 illustrates Example No. 3 above, with certain omissions as hereinafter explained.

Re erring now to Fig.1, ll illustrates a converter with a spout l2 and tuyres l3; and I4 illustrates a ladle. At point 1, after initial charging, the converter carries matte IS on which is floating flux it. At point 2, the converter is tilted and the blast is on. At point 3v the converter is upright, the blast is off and we have a mass of white metal I! on which floats slag I8. At point 4 the converter is tilted forward to pour the slag l8 into a ladle, holding back the white metal.

In order to increase the quantity under treatment the converter is turned back from point'4 to point 5 and on top of the white metal I1 is applied a further charge of matte l5 and flux l6. At point 6 the blowing is renewed. Points '7 and 8 are practically repetitions of 3 and 4 except for the increased volume of white metal in the converter. peated to any desired extent, after which the white metal is blown to blister copper which is held molten in a furnace until ready to be conveyed to the pig casting machine and the pigs to the refinery. i

.In carrying out Example No. 1, the steps are the same as in Fig. 1 until the required quantity of molten white metal is accumulated in the converter; after which they are as illustrated in Fig. 2. The white metal I1 is blown at point 9 for the short period stated. The blast is stopped, point 10, and the converter held upright long The same steps may be reenough to permit the comparatively high gold copper I9 to settle out of the comparatively low gold white metal 20. At point 11 the low gold white metal 20 is poured off into a ladle l4,

and at point 12 the converter is further tilted to pour of! the high gold copper i9 into a second ladle II. This comparatively high gold copper may be transferred to point 1 (Fig. 1) of an ordilow gold blister copper 2|, which is poured into a ladle 8 and thence to a holding furnace 22 (point 17), whence it passes to the pig casting machine.

In carrying out Example No. 2, the process of Fig. 1 is practiced until a sufllcient quantity of 'white metal is accumulated in two converters A and B (Fig. 3). The metal from B is transferred to A (point 10) by way of a ladle lt Thence it is blown (point 11) and held.(point 12) until there is an accumulation of comparatively high gold bearing copper I9 at the bottom of the low gold bearing white metal 20. At point 13 the white metal 20 is transferred by means of a ladle 14 to a converter B.

At point 14 the high gold copper i9 is poured into a ladle I4 and transferred to point 1 (Fig. 1) of an ordinary converting process, or otherwise utilized. The converter B is tilted and the blast turned on to blow the white metal 20 to blister copper 2|, point 15, which is disposed of as in Fig. 2.

Example No. 3 (Fig. 4) also utilizes two converters A and B of white metal i1. At point 10 it transfers the same from B to A, blows briefly, point 11, settles, point 12, and pours oil the low gold bearing white metal 20 into converter B while retaining the high gold bearing copper IS in converter A, point 13.

Then commences a new cycle. While the white metal 20 in converter B is blown to low gold blister copper and finally conveyed to the pig casting machine, as in Fig. 3, the high gold bearing copper 19 in converter A is further enriched. The converter is held upright and matte i and flux 16 are added, point 14. The mass is blown,

point 15, for a short time and the converter then rlghted while the matte settles, point 16. The slag i8 is poured ofl. (point 17) into a ladle and taken to reverberatory furnaces, or otherwise disposed of. a

This leaves in converter A a small quantity ll of high gold white metal. To this are added matte l5 and flux i6, whilematte and flux are also put into converter B, bringing us to point 18. A number of cycles following are omitted from Fig. 4 for brevitys sake, being shown in other figures. Both converters are blown to white metal and skimmed to remove slag as in points 2, 3 and 4 (Fig. 1); bringing about the condition of point 9 except that the white metal in converter A has acquired a higher gold content than that in B, which is the same as it was originally. The white metal poured off from B is then transferred to A, as in point 10, blown briefly as in point 11, held for settlement as in point 12 and the white metal poured oil into B in point 13, leaving in A a still higher gold content in the bottom.

ccncentration process is repeated through from two to sixteen of the described cycles. At point 19 is iiiustrated the end of the last cycle.

The final batch of low gold copper is made from the white metal 20 in B in the usual way. The enriched bottom IS in A is supplemented by a further charge of matte I5 and flux 46 (point 20) and converted by the ordinary procedure, yielding a high gold blister coppen.

Various modifications ot'the processes above described may be made by those skilled in the art without departing from the invention as defined in the following claims.

What we claim is:

1. In the selective converting of copper matte containing gold, the method which consists in blowing such matte to white metal, subjecting the white metal to a partial blow so short as to convert only a comparatively small percentage of the copper originally in the matte into particles of metallic copper disseminated throughout the mass of white metal, and holding the charge quiet over so long a period as to permit a long, settling out of the fraction "of copper converted, the particles of copper disseminated throughout the mass during the short blow and long settling period providing a large goldcollecting surface in contact with the matte so that the fraction settled out has a comparatively high gold content, said method being practiced with two converters A and B, by the partial blowing and long settling of the double charge of white metal in A and the collection of a small fraction of high gold copper therein, the pouring of the remaining white metal into B and the blowing of it therein to copper of comparatively low gold content, the removal of such low gold copper from B and the refilling of B with matte and flux, the addition to the molten bottom in A of new matte and flux, the blowing of the charge in the two converters to produce white metal, the transfer of the white metal from B to A and the repetition of the previous steps so as to extract additional gold in a single bottom in converter A until a bottom of the desired enrichment is obtained.

2. In the selective converting of copper matte containing precious metals, the process which consists in blowing a charge of matte in one converter A to form white metal and metallic copper, the metallic copper comprising about 25% of the total amount of copper values in the charge containing the major proportions of the precious metals, transferring the residual white metal to a second converter B and blowing it therein to metallic copper, blowing the metallic copper in converter A with successive charges of white metal to transfer the precious metals from the white metal to the copper metal and successively transferrlng the residual white metal of said charges after treatment with metallic copper to converter B and converting said residual treated white metal to metallic copper in converter B.

3. The process of claim 2, in which matte is freed from slag in converter B and supplied therefrom to converter A between the conversion of charges of white metal low in precious metals received from converter A.

4. In the selective converting of copper matte containing precious metals, the process in which a charge of copper metal is incorporated in successive charges of copper matte in a converter A, blowing said matte to reconvert said metal enriched with precious metal values and leave a residual white metal impoverished in precious metal values and successively converting said residual impoverished white metal in a second converter B.

5. The process of claim 4, in which the proportions of metallic copper to the copper content n 

